Trabecular Bone score (TBS), a novel tool derived from DXA, reflects the microarchitecture of the vertebrae. It has been shown to predict fracture independent of standard DXA parameters in adult populations. Previously, we demonstrated that maternal serum 25-hydroxyvitamin D (25(OH)D) during pregnancy was associated with offspring bone mineral content at age 11yr. However, associations between maternal 25(OH)D and offspring TBS have not been explored.
Data were collected from the Vitamin D in Pregnancy (VIP) study (baseline 2002-04), a cohort of 475 pregnant women recruited from the Geelong Hospital in early pregnancy (gestation 12.6±2.8wk). Venous blood samples were taken at recruitment and at 28-32 weeks gestation. Maternal serum 25(OH)D was measured by radioimmunoassay (Immunodiagnostic Systems). Offspring (n=195, n=181 with complete measures) underwent spine DXA (GE Lunar), at age 10-12yr (median: 10.9 (IQR 10.9-11.4)). TBS was calculated using TBS iNsight software (Version 2.2, Med-Imaps).
Offspring of mothers with sufficient 25(OH)D levels (≥50nmol/L) at recruitment had a higher TBS (1.363 vs 1.340, p=0.04). Maternal 25(OH)D and offspring TBS were weakly correlated (r=0.16, p=0.02). After adjustment for child height, sex, pubertal stage, lean mass and fat mass, a 10 nmol/L increase in maternal 25(OH)D was associated with a 0.005 (95% CI 0.0001, 0.010) increase in TBS. The associations were more robust in boys (β 0.008, 95%CI 0.0004, 0.015) than girls (β 0.001, 95%CI -0.005, 0.008); however, a 25(OH)D*sex interaction was not significant (p=0.20). Adjustment for maternal factors and season of serum sample did not materially alter these associations. There were no associations with TBS and maternal 25(OH)D at 28-32 weeks.
Maternal 25(OH)D in early pregnancy was associated with impaired vertebral microarchitecture in offspring at age 11. These findings warrant confirmation with interventional and long term follow-up studies, as optimising 25(OH)D during early pregnancy may favourably influence offspring TBS.